Die for forming folded, angular or rounded corners on leather or the like



Apnl-24, 1956 .l. B. ROSENTHAL 2,

DIE FOR FORMING FOLDED, ANGULAR OR ROUNDED CORNERS 0N LEATHER OR THE LIKE Filed Aug. 29, 1955 4 Sheets-Sheet l .Z j 7. INVENTOR.

JULIAN B- ROSEN'IHAL an L,

p i 24, 1956 J. B. ROSENTHAL 2,742,775

DIE FOR FORMING FOLDED, ANGULAR OR ROUNDED CORNERS 0N LEATHER OR THE LIKE Filed Aug. 29', 1955 4 Sheets-Sheet 2 INVENTOR. JULIAN B- ROSENTHAL pr 4, 1956 J. B. ROSENTHAL 2,742,775

- DIE FOR FORMING FOLDED. ANGULAR OR ROUNDED CORNERS DN LEATHER OR THE LIKE Filed Aug. 29, 1955 4 Sheets-Sheet 3 JNVEN TOR. JULIAN b. ROSENTHAL pri 2-4:, 1956 J. B..ROSENTHAL 2,742,775

DIE FOR FORMING FOLDED, ANGULAR OR ROUNDED CORNERS ON LEATHER OR THE LIKE Filed Aug. 29, 1955 4 Sheen's-Sheer 4 .INVENTOR. JULIAN E). ROSEIN'IHAL United States Patent Q DIE FOR FORMING FOLDED, ANGULAR on ggclNDED CORNERS N LEATHER on THE Julian B. Rosenthal, New York, N. Y. Application August 29, 1955, Serial No. 531,065

' 12 Claims. (Cl. 69-1) This invention relates to an improved die used in the leather working or related arts, such as in the manufacture of wallets, key cases, card holders, etc. More particularly, the invention has reference to a die that is particularly adapted to act upon a single piece or superposed pieces of leather or similar flexible material, in such a manner as, in a single operation, to fold a'rounded or angular corner on said piece or pieces, While at the same time precreasing the article to facilitate the formation of a flat corner fold.

Stated broadly, the invention comprises a die which, in a single downward blow or thrust of an associated ram or piston, will first corrugate or prec'rease a flat piece or pieces of leather placed therein, and, at a subsequent stage in the continued downward thrust of the ram, will turn upwardly the creased marginal portion of the work piece and, finally, at the terminal stage of the downward thrust, will fold over the upwardly turned marginal" part of the piece to complete the creasing" and folding opera tion.

By reason of a die formed as stated, the manufacturing operations can be carried out more rapidly, through the reduction of a plurality of steps that are now required in the working of the leather, since, by mere placement of the raw or unfinished work piece in the die, and by the imposition of the single downward thrust upon the movable portion of the die, the piece is finished with a folded over marginal portion and with an angular'or straight rounded corner having a corrugated or creased construction, for the purpose of flattening out the portion of the leather material that would otherwise be in excess-at the corner and would represent an undesirable projection upon the finished article at the corner portion thereof;

A further object is to form a die as described which can be used at relatively high speed, thus to provide for uantity production of the finished article's.

Still another object is to form the die in such manner as to facilitate substitution of different work piece-contacting die portions, to finish various work pieces in different ways, according to the size and the desired finished configuration ofthe articles being produced.

Still another object is to form a die as described which will be of rugged construction, will be substanitially trouble free in operation, and will not, considering the results capable of attainment thereby, be high in manufacturing cost and in cost of regular operation. 7

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly setforth.

In the accompanying drawings forming a material part of this disclosure:

Fig. 1 is a side elevational view of a die formed according to the present invention, in association with a workpiece and ram both of which are shown fragmen tarily and in section, the die being shown in its first or 2,742,775 Patented Apr. 24, 1956 2 {inoperative position, the work piece being shown in dotted HES.

' Fi 2 is a front elevational view of the die separate from the supporting table and ram, the work iece again being shown in dotted line's.

Fig. 3 is a sectional view on line 33 of Fig. 2 showing in top plan the lower assembly of the die.

Fig. 4 is a sectional view on line 4-4 of Fig. 2.

Fig. 5 is a sectional view on line 5-5 of Fig. 2.

Fig. 6 is a fragmentary vertical section on line 6-6 of Fig. I.

v .Fig. 7 is an enlarged perspective view of one of the stop blocks shown in Fig. 6, per se'.

Fig. 8 is a front elevational View of the die after the first step in the operation.

Fig. 9 is a front elevational view next step in the operation. v Fig. 10 is a fragmentary front elevational view of the die after the final step of the operation.

Fig. If is a fragmentary perspective view of the work piece as it appears following the-operational step shown thereof showing the 'in Fig. 8.

Fig. 12 is a viewer the work piece similar to Fig. 11, showing the same after Fig. 9 step of the opera tion.

' Fig. 13 is a view of the work piece similar to Figs. 11 and 12, showing the same after the step of the operation depicted in'Fig'. IO. r

The reference numeral 10 generally designates a die formed according to the present in etition, mounted u on a work table 12, in association with a ram 14'. v

The die includes a stationary base 16, of rectangular outer configuration, to" the underside of which, adjacent the front edge of the base, there isfixedly attached adepending, cylindrical leg 18 formed at its lower end with a reduced threaded axial xtension 20. Theleg is adapted to extend through an opening ZZ'fcSr'med in the support;

ing table, after which a nut 24 is threaded onto irtension securely bolt the base thereto.

Fixcdly secured to the base is a lower die sup -ort'bloclt 26 having in its front surface a wide, v-shaped recess 28. up er surface of the block 26,. at the back ofthe block, is formed with a shallow transverse recess so cxtending overtlie full width of the block as shown in Figs. 1 and 3, and removably and fixedly secured within recess 20, hearing against theundersid'c the work table. to a l 30, by hold-down bolts or screws 32-, is a stationary lower reasing or corrugating die member 34 having medially between its opposite ends a plurality of straight, elon at d teeth or ribs 36 radiating from a commo center disposed inwardly from the corner or the V-shaped front recess as shown in Fig.3. Opening upon the upper and back surfaces of the die member 34 is a square recess 38 iuten ru ting the series of radially extending teeth 3'6. v

The work piece to be acted upon by the assemblyhas been designated by the reference letter W and only a frag mentary portion thereof is shown in the various figures of the drawing; In the illustrated example, only a single thickness of a work iece is shown, but in accordance with the invention, the work piece may constitute" a flexible piece of feather or the like, themarginal portion of which is to be creasedand corner folded, in association with a flat relatively rigid backing member over which said corner is to be folded. For the purpose of more clearly explaining the construction and the folding. rocess, only a single thickness is shown, the corner of which is to be folded-onto the body art thereof.

The corner of the work piece is positioned against the guides 40, formed as low, flat pieces secured rcmovably to the top surface of the block 26 by hold-down screws 42. The guide pieces have slots 44 formed therein, receiving the shanks of the screws 42, thus permitting adjustment of the guide pieces toward or away from the adjacent edges of the forwardly opening, V-shaped recess 28 of the block 26. The inner, work piece-contacting surfaces of the guide pieces, as shown in Fig. 3, are in parallelism with the adjacent walls of the recess 28, but are spaced outwardly from said recess walls a distance sufi'icient to permit support of the opposite side edge portions of the work piece upon block 26.

Within the upper portion of the recess, there is provided a vertically movable work piece support plate 46, of triangular formation, the side edges of which are in sliding contact with the side walls of the recess. The plate, as shown, is of laminated construction, but alternatively, could be of a single thickness of material.

Secured to the underside of plate-46, within recess 23, is a stem or plunger 48, axially slidable within a vertical bore formed in base 16, leg 18, and axial extension 20, said bore opening upon the upper surface of the flat base 16 and upon the lower end of the extension 20. The stem 48 has a compression spring 50 coiled thereabout within the recess 23, and said spring normally elevates the plate 46 to a position in which its top surface is coplanar with the top surfaces of the lower die member 34 and block 26.

Threaded onto the lower end of the stem 48 are adjusting nuts 52, one of which constitutes a lock nut, said nuts being threadable to selected positions along the length of the stem 48, for regulating the extent to which the spring 50 can shift the plate 46 to its upper position. In the upper position of plate 46, the nuts 52 engage against the lower end of the axial extension 20.

Limiting the downward movement of plate 46 is an angular series of upwardly projecting screws 54, threaded in the bottom wall of the recess 28, in closely spaced relation to the angularly related side walls of the recess. Screws 54 can be threaded upwardly or downwardly as necessary, to limit the downward movement of the plate 46 to a selected, adjusted extent.

In the upper surface of the die member 34, and in the block 26, there are formed transversely spaced, parallel, vertical bores in which are slidably engaged guide rods 56 about which are circumposed springs 58. Secured to the upper, projecting ends of the guide rods is an upper, movable creasing die member 60 having a forwardly opening recess 62 in the shape of a shallow V, which has its edges substantially in registration with the angularly related meeting portions of the side walls of recess 28.

As shown in Fig. 5, on the underside of the upper creasing die member 60 there is formed a series of teeth 64 which complement the teeth 36 of the lower creasing die member.

Adjacent the back edge of the die member 60, medially between the opposite ends of said die member, there is fixedly secured thereto an upwardly projecting, vertical plunger 66 which, when shifted in a downward direction, is adapted to bring the upper die member 60 into engagement with the lower die member 34, to corrugate or crease the corner portion of the work piece W between the mating teeth thereof.

At its upper end, plunger 66 is slidably engaged in an opening 68 (Fig. 6) formed in an upper die plate 70.

Plunger 66 is slidable within an opening 68 formed in a fiat, rectangular upper support plate 70, and at its upper end has a reduced portion 72 provided at its base with a frusto-conical shoulder 73.

In the normal position of the device shown in Figs. 1 and 2, the reduced extension 72 is engaged by and between the inner ends of a pair of blocks 74 one of which is shown per se in Fig. 7. The blocks 74 are slidably mounted upon the upper surface of the plate 70, adjacent the back edge thereof, and their construction and normal relationship relative to plunger 66 is illustrated in Fig. 6 to its best advantage. As there shown, the blocks 74 have adjacent their inner ends longitudinal, closed, short guide slots 76, and extending through said slots 76 are hold-down screws 78, threaded into the upper surface of the plate 70. The blocks are thus mounted upon the plate for limited sliding movement in opposite directions. and, when in engagement with extension 72, receive said extension 72 in confronting, semicircular recesses 80, with the lower edges of the recesses 80 of the blocks being disposed at the upper or smaller end of the shoulder 73.

A pair of upstanding, rectangular plate members 82 is provided upon the plate 70, these being secured to the opposite side edges of plate 70 by screws 84. The plates or cars 82 have threaded openings, in which are engaged spring tension adjusting screws 86. Screws 86 are provided with reduced inner ends, slidably engaged in counterbored recesses formed in blocks 74, and held under compression between the blocks 74 and the shoulders defined on the screws 86 by the reduced inner end portions thereof are springs 87. The springs 87 normally shift the blocks 74 toward one another, into engagement with ex tension 72, and the tension of the springs is adjusted by threading of the screws 86 inwardly or outwardly, as the case may be.

Fixedly secured to the underside of the plate 70, is a triangular upper die member support plate 83, and fixedly secured to the underside of plate 88 is an upper die member 90. This is also of triangular formation, with its edges in registration with those of the plate 88. In the underside of the upper die member 90 there is formed a triangular recess 92, spaced inwardly a distance from the side edges of the plate 90 to define on the plate 90 a depending, V-shaped rib 94, the bottom surface of which, along the outer edge of the rib, has a continuous. gently curved longitudinal lip 96.

Disposed below the upper die member 90, with its several edges in registration with the walls of the recess 92, is a triangular pressure plate 97. This is carried by a vertical stem 98, about which is circumposed a compression spring 100, one end of which abuts against the plate 97 and the other end of which abuts against the inner wall of a counterbore formed in plate 90, and constituting a continuation of a vertical bore in the plate 90 and plate 88 in which the upper end portion of the stem 98 is slidable.

To prevent the hold-down or pressure plate 97 from turning about the axis of stem 98, there is provided a. guide stern 102, secured to the back or apex portion of plate 97, and slidable in a downwardly opening bore formed in the upper die member 90 and plate 8?.

ln use of the device, it is secured to the work table 1.4 in the manner shown in Fig. l, and the movable die assembly constituted by plate 70 and the parts carried thereby is engaged with the lower end of a tubular ram 14, which can be hydraulically or otherwise actuated. To this end, the plate 70 has rigidly secured to the upper surface thereof an upstanding projection 104, having a reduced axial extension defining a shoulder on the projection 104 engaging the ram 14 with the extension 106 extending into said ram.

The work piece W is positioned as shown in Fig. 3, with its corner portion overlying the teeth 36. Then, downward movement of the ram is initiated, and initially. the guide blocks, by reason of the pressure exerted thereagainst by springs 87, will be held in engagement with extensions 72, and will resist spreading by the shoulder 73 of plunger 66. Therefore, during the initial downward movement of the upper die assembly, plunger 66 will be moved downwardly bodily therewith, shifting the upper corrugating die member 60 downwardly into engagement with the upper surface of the work piece W.

The parts will now appear is in Fig. 8, from which it is seen that when the upper corrugating die member 60 is shifted downwardly into engagement with the work plunger 66 cannot move further in a downward direction,

despite the continued downward movement of the plate 70 carrying blocks 74.

As soon as the blocks 74 are spread by shoulder 73, and the main diameter portion of the plunger 66 is in engagement with the inner ends of the blocks, the plunger 66 will be free to move upwardly relative to the stationary lower die assembly, under the force of the spring 68. Therefore, the upper corrugating die will now immediately shift upwardly out of engagement with the work piece, to the positionshown in Fig. 9. a

Fig. 9 shows the next stage of the operation. The continued down stroke ofthe ram now brings the-holddown plate 97 against the work piece W, said hold-down plate having its edges spaced inwardly from the edges of the work piece.

the upper dieassembly the work piece support plate 46, said plate 46, and the workpiece, moving-downwardly into the recess 28 as shown in Fig. 9.

Since the marginal or edge portion 110 of the work piece projects initially beyond the edges of the recess 28, said marginal portion will, at this stage of the operation, be bent upwardly as shown in Fig. 9 and also in Fig. 12, with the upwardly deformed marginal part 110 in engagement with the side walls of recess 28.

At the completion of this stage of the operation, plate 46 comes to rest against the stop screws 54, and. now, as shown in Fig. 10, in the next stage of the operation the upper die member 90 will engage the marginal portion of the work piece, with plate 97 recessing, against the restraint of its associated spring 100', within recess 92 of the upper die member 90.- The lip 96 of the rib 94 engages the upwardly projecting marginal part 110 of the work piece, and folds the same inwardly, after which the underside of the rib 94 exerts a strong downwardpressure at the completion of the operation to complete the folding operation, flattening the corrugations 108 and forming a folded marginon the work piece W as shown in Fig. 13.

' It will be apparent that the construction is such that in a single down stroke of a r'am, the comer of the work piece is corrugated, the marginal portion of the work piece is turned upwardly, and then, the corrugated corner and marginal part are folded inwardly into a flattened condition, thus performing the entire operation with a minimum of manufacturing steps and in a minimum amount of time, to permit quantity production at relatively low cost.

When the ram is lifted, the parts return automatically to their normal positions, due to the expansion of spring 50' which shifts the work piece supportplate 46 to its upper, normal condition shown in Fig. ,8, and due fun ther to the expansion of spring 100 which moves plate 97 downwardly out of recess 92. When the upper die assembly moves to its uppermost position responsive to elevation of the mm, the blocks 74 again move into engagement with the'reduced extension 72, awaiting the repetition of the operation on the next work piece.

-While I have illustrated and described the preferred embodiment of my invention, it isto be understood that I do not limit myselfto the precise construction herein disclosed and that various changes and modifications may be made within the scope of the invention as de fined in the appended claims.

Therefore, as the down stroke of the 7 ram continues, there will now move downwardly with Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patout is:

1; Apparatus for corrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper,

folding die afiixed to said upper support, an upper, corrugating die connected to both the lower and upper sup? ports for vertical sliding movement relative to each of said supports and normally spaced above the lower corrugating die, means releasably interengaging the upper eorrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper corrugating die engaged with the upper support for movement therewith, cooperating with the lower cortugating dieto corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper corrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the workpiece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plate engaged against further downward movement by the lower support, this to fold over the corrugated marginal portion of said workpiece.

2 Apparatus for corrugating andfolding. the inner portion of a piece of flexible material, comprising a station ary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the 'recess, a stationary lower corrugated die on said' lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die affixed to said upper support, an upper, corrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower corrugating die, means releasably interengaging the upper corrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugat: ing die, on lowering of the upper support with the u er corrugating die engaged with the upper support for movement therewith, cooperating with the lower corrugatin-g die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper corrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movementof the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plateengaged against further downward movement by the lower support,thu"s to fold over the corrugated marginal portion of said work piece, the corrugating die including adie member and a plunger secured thereto, said means comprising a pair of blocks slidably mounted upon the upper die support and spring loaded in a direction to engage against the plunger, the plunger having a reduced axial extension at its upper end engaged by said blocks to interengage the plunger and upper die support for joint vertical movement.

3. Apparatus for eorrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die afiixed to said upper support, an upper, eorrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower eorrugating die, means releasably interengaging the upper eorrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper eorrugating die engaged with the upper support for movement therewith, cooperating with the lower eorrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper eorrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, the eorrugating die including a die member and a plunger secured thereto, said means comprising a pair of blocks slidably mounted upon the upper die support and spring loaded in a direction to engage against the plunger, the plunger having a reduced axial extension at its upperend engaged by said blocks to interengage the plunger and upper die support for joint vertical movement, said plunger having a frusto-conical shoulder at the base of said reduced extension, whereby, following joint vertical movement of the plunger and upper die support, said shoulder will spread the blocks against the restraint of the spring loading thereof to free the plunger and upper die support for relative sliding movement.

4. Apparatus for eorrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die affixed to said upper support, an upper, eorrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower eorrugating die, means releasably interengaging the upper eorrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper eorrugating die engaged with the upper support for movement therewith, cooperating with the lower eorrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper eorrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, said recess being of triangular formation for disposition of the corner portion of said work piece thereabove with its marginal portion seated upon the lower die support adjacent the edges of the recess, the work piece support plate, hold-down plate, and folding die being of corresponding triangular configuration.

5. Apparatus for eorrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die aflixed to said upper support, an upper, eorrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower eorrugating die, means releasably interengaging the upper eorrugating die with the upper support for vertical slidmovement therewith, a work piece hold-down plate vertically siidable on the upper die support and normally disposed above the work piece support plate, said upper eorrugating die, on lowering of the upper support with the upper eorrugating die engaged with the upper support for movement therewith, cooperating with the lower eorrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper eorrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the. work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the holddown plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, said recess being of triangular formation for disposition of the corner portion of said work piece thereabove with its marginal portion seated upon the lower die support adjacent the edges of the recess, the work piece support plate, hold-down plate, and folding die being of corresponding triangular configuration, said lower eorrugating die being mounted upon the lower support adjacent the apex portion of the recess, for disposition below the corner of the supported work piece.

6. Apparatus for eorrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die affixed to said upper support, an upper, corrugating die connected to both the lower and upper supportion of said work piece, said work piece support plate being spring biased in an upward direction within the recess, and being connected to the lower support for adjustment of its normal position within the recess.

10. Apparatus for corrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die affixed to said upper support, an upper, corrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower corrugating die, means releasably interengaging the upper corrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper corrugating die engaged with the upper support for movement therewith, cooperating with the lower corrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper corrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said holddown plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, said recess being of triangular formation for disposition of the corner portion of said work piece thereabove with its marginal portion seated upon the lower die support adjacent the edges of the recess, the work piece support plate, hold-down plate, and folding die being of corresponding triangular configuration, said lower support including guides disposed adjacent opposite sides of said recess for engaging the edges of the supported work piece.

ll. Apparatus for corrugating and folding the inner portion fo a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die alfixed to said upper support, an upper, corrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower corrugating die, means releasably interengaging the upper corrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper corrugating die engaged with the upper support for movement therewith, cooperating with the lower corrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper corrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece against the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the holddown plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, said recess being of triangular formation for disposition of the corner portion of said work piece thereabove with its marginal portion seated upon the lower die support adjacent the edges of the recess, the work piece support plate, hold-down plate, and folding die being of corresponding triangular configuration, said lower support including guides disposed adjacent op posite sides of said recess for engaging the edges of the supported work piece, said guides being mounted upon the lower support for adjustment toward and away from the edges of said recess.

12. Apparatus for corrugating and folding the inner portion of a piece of flexible material, comprising a stationary lower die support having an upwardly opening recess, a work piece support plate vertically shiftable within the recess, a stationary lower corrugated die on said lower support adjacent the recess, a vertically movable upper die support above the lower support, an upper, folding die affixed to said upper support, an upper, corrugating die connected to both the lower and upper supports for vertical sliding movement relative to each of said supports and normally spaced above the lower corrugating die, means releasably interengaging the upper corrugating die with the upper support for vertical sliding movement therewith, a work piece hold-down plate vertically slidable on the upper die support and normally disposed above the work piece support plate, said upper corrugating die, on lowering of the upper support with the upper corrugating die engaged with the upper support for movement therewith, cooperating with the lower corrugating die to corrugate a corner portion of said work piece, said last-named means being adapted for disengaging the upper corrugating die following corrugation of said work piece to free the upper support for further downward movement toward the lower support, said hold-down plate being disposed for engaging the work piece following corrugation of the same to shift the work piece and the work piece support plate downwardly within said recess, thus to fold upwardly the marginal portion of the work piece aganst the wall of the recess, further downward movement of the upper support being adapted for shifting the folding die against the upwardly turned marginal portion of the work piece with the hold-down plate, work piece, and work piece support plate engaged against further downward movement by the lower support, thus to fold over the corrugated marginal portion of said work piece, said recess being of triangular formation for disposition of the corner portion of said work piece thereabove with its marginal portion seated upon the lower die support adjacent the edges of the recess, the work piece support plate, hold-down plate, and folding die being of corresponding triangular configuration, the lower and upper corrugating dies having elongated, complementary, corrugating teeth radiating from the apex of said recess.

No references cited. 

